Intellij syntax error: "Application does not take parameters"

[chrisbenincasa]

Hello, I'm wondering if there's a way to get IntelliJ (I'm using v15.0.6 with Scala plugin 2.2.0) to be able to recognize the implicit conversion to a Mapper when applying an Endpoint.

Screenshot:

The reported error is "Application does not take parameters". Of course, this error is spurious (the code compiles). IntelliJ just seems to have some trouble with the conversion of my functions to Mappers (and probably also to FnToProduct). Not sure if this is a common issue for people using Finch in IntelliJ. Any help would be greatly appreciated!

[vkostyukov]

Thanks @chrisbenincasa!

I'm (and I think everyone else is) aware of this problem. One workaround I use is to disable type-checker in IntelliJ (hit that green [T] in the right bottom corner). Although, this basically disables the everything in the IDE besides autocompletion. I think the best we can do here is to file a ticket against the Scala plugin (and vote it!) and mention this problem as false-alarm. They usually respond quite promptly.

I personally nearly hate this "magnet pattern" thing we use as Mapper to allow this DSL-like syntax. I have some ideas how to make it more explicit (extract the syntax layer into its own namespace) and perhaps simplify. Although, this doesn't mean IntelliJ shouldn't support this pattern. Lots of Scala libraries use it and I think, the Scala plugin is making a quite a decent progress in better supporting it.

[od0]

Just a note - this appears to not be an issue in 2016.2, but resurfaces in 2016.3 (along with other unrelated Scala bugs)

Here is a link to download the latest good release, 2016.2.5: https://confluence.jetbrains.com/display/IntelliJIDEA/Previous+IntelliJ+IDEA+Releases

[chrisbenincasa]

@od0 interesting. I'm on 2016.3.1 (Scala plugin 2016.3.5) and the error has changed slightly:

Basically that, but for every endpoint.

Sorry for the delay, but thank you for the reply, @vkostyukov. I'll look into opening up an issue on the Scala plugin.

[bergmark]

Has anyone reported this bug on the scala plugin issue tracker?

[chrisbenincasa]

@bergmark This totally slipped my mind; I never opened up an issue.

[rpless]

I've seen noticeably fewer of these errors after switching to the 2017 EAP release. And the errors are usually fixed by invalidating caches. Has anyone else tried the EAP?

[od0]

@rpless I'm on the latest EAP now and it's as bad as ever :/

[manub]

Having a problem which may be related to this with the Hello World example. Both on IntelliJ 2016.3 and 2017 EAP. sbt compile works. Invalidating caches didn't help. Using Scala 2.12.

[vkostyukov]

I went ahead and filed an Intellij ticket (against Scala plugin): SCL-11386.

[marceloboeira]

My 2 cents:

That does not raise the warning:

  val api: Endpoint[String] = get("hello") { Ok("Foo") }

However, this raises it:

And if I declare the params, it does not compile at all:

[marceloboeira]

It seems that everything works if updated to:

IntelliJ IDEA 2017.2
Build #IC-172.3317.76, built on July 15, 2017
JRE: 1.8.0_152-release-915-b5 x86_64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Mac OS X 10.12.6
Scala Plugin: 2017.2.5

[ssenge]

@marceloboeira: I have the same setup but run into these issues, it is compilable though:

[marceloboeira]

@ssenge they've disappeared after I updated the IDE/plugin. For me, it was compiling only over the terminal, but not from the IDE.

[ssenge]

@marceloboeira: Compilable from IDE but wrong error highlighting :( Everything updated and rebuild.

[sergeykolbasov]

This one should be solved now with #858

[vkostyukov]

I think we're in a good place to close this. We can always re-open if things get broken again. Huge thanks to @sergeykolbasov for taking a stub on fixing this!

[acidghost]

I'm having issues with IntelliJ 2018.3.4 and finch 0.27.0. In the following snippet

val forSale: Endpoint[F, Seq[Product]] =
  get("products" :: "for-sale" :: param[DeliveriesDayOfWeek]("dow")).mapAsync {
    dow => productService.forSale(dow)
  }

the IDE wrongfully thinks that dow is of type DeliveriesDayOfWeek :: HNil, while is instead a DeliveriesDayOfWeek. The code compiles just fine.

[vkostyukov]

@acidghost Thus is surprising to me. I was under the impression it was fixed quite some time ago. I'd recommend leaving a comment on a linked IJ ticket with your reproducer.

[sergeykolbasov]

Yep, I can reproduce it, though it's a different problem not related to Mapper anyhow.
We have a custom PairAdjoin that for a composition with single element returns A instead of A :: HNil. I think IDEA fails to understand it.